The integration density of different electronic components is continuously improved in the semiconductor industry. Continuously decreasing the minimum size of the components allows more and more components to be integrated in a given area. For example, the trench gate metal-oxide-semiconductor field effect transistor, which is widely applied in power switch components, is designed to have a vertical structure to increase the functional density. In a trench gate metal-oxide-semiconductor field effect transistor, the back side of the chip serves as a drain, and the sources and gates of various transistors are formed at the front side of the chip.
However, as the functional density of semiconductor devices continuously increases, the complexity of processing and manufacturing semiconductor devices also increase. For example, due to the restrictions of the alignment ability of traditional lithography machines, the scaling-down process of the feature size of the trench gate metal-oxide-semiconductor field effect transistors cannot be carried out. Therefore, the on resistance of semiconductor devices cannot be decreased effectively.